Certain components of pharmaceutical, nutraceutical and cosmetic compositions are known to undergo unwanted degradation and/or chemical alterations, affecting the quality or shelf-life of such products. For instance, surfactants can degrade to generate unwanted components, e.g., polysorbates can yield unwanted carbonyl degradation products.
Surfactants are used in emulsions. The vaccine adjuvant known as “MF59” [References 1-3] is a submicron oil-in-water emulsion of squalene, polysorbate 80 (also known as TWEEN® 80), and sorbitan trioleate (also known as SPAN®85). It may also include citrate ions, e.g., 10 mM sodium citrate buffer. The composition of the emulsion by volume can be about 5% squalene, about 0.5% TWEEN® 80 and about 0.5% SPAN®85. The adjuvant and its production are described in more detail in Chapter 10 of Reference 4, chapter 12 of Reference 5 and chapter 19 of Reference 6. Polysorbate 80 and squalene are also present in the emulsion adjuvant known as “AS03” [Reference 16].
Polysorbates can undergo autooxidation, generating peroxides, aldehydes, ketones and acids. Other components in a composition, such as proteins, can be affected by some of these degradation products. For instance, conformation of proteins can change, which can affect their efficacy [References 7, 8].
In addition, squalene has been shown to undergo oxidative degradation resulting in the generation of carbonyl by-products. Photo-oxidative cleavage of squalene has been shown to produce formaldehyde, malonaldehyde, acetaldehyde and acetone [References 9], although degradation can be reduced by storage in an air-tight container, storage under nitrogen, protection from light, etc.